In the prior art there are extant various modes and systems for facilitating the stacking of sheets on or in a receiving tray, including the following prior art.
Lawrence U.S. Pat. No. 5,649695, granted Jul. 7, 1997 discloses a continuous finishing apparatus for copiers and printers in which sheets exiting the host machine are supported at their trailing edge on a retractable shelf and on their leading ends on a mechanism which is laterally shiftable. The shelf is retracted and the laterally shiftable mechanism is opened to allow the sheets to fall upon a stacker, after a set of the sheets has been finished.
In the pending application of Coombs, Ser. No. 09/078,202, filed May 14, 1998, commonly owned herewith, sheet finishing apparatus is shown having vertically spaced pairs of trays which are laterally pivotable to allow the sheet to progressively move downwardly to a stacker during the finishing of sheets by stapling or binding.
In essence, the state of the prior art appears to be that it is well known to support sheets and accumulate sets of sheets for binding or stapling on devices which finish the sets of sheets and then move the sheets to a stacker or receiver, as more particularly shown in Hiroi, et al U.S. Pat. No. 5,385,340, granted Jan. 31, 1995, wherein the sheets are arranged in a stack supported partially on a stacker and partially on a ledge from which the finished sets of sheets are pushed so as to rest entirely on the stacker.